Synchronizing apparatus



June 7, 193s. P. B. AGNEw 2,120,140

SYNCHRONIZ `ING APPARATUS Filed Oct; 4, 19344 FIGA P165 Patented June 7, 1938 l 2,120,140 sYNcHRoNizING APPARATUS Prentiss Boyd Agnew, Atlanta, Ga. Application October l4, 1934, Serial No. 746,920

1 Claim.

Generically this invention relates to a measuring or calibrating device, but is more particularly directed to a device for determining the error in the running/of machines by the synchroniza- 5 tion of sounds. A

One of the principal objects of this invention is the provision of a device for determining the amount of and the direction of the error in the running of watches and also of clocks whose operations, as time-keeping devices, are controlled by balanc wheels or pendulums.

Another important object of this invention is the provision of a device for determining the amount of and the direction of the Aerror in the frequency of alternating `current supply systems.

A still further important object of this invention is the provision of a device for determining the amount of and the direction of theerror in the running of rotary machines which are designed for constant speed operation.

When used as a device for making these tests on watches or clocks and the like it consists essentially of two parts; the one, an electrical circuit containing a microphone and a receiver so ar- 25 ranged that when the watch or clock to be tested f is placed near the microphone the sound of the beats or ticks can be heard by the ear in the receiver; the other, a synchronous motor which is used as a master device and is connected to the microphone-receiver circuit through an adjustable contact in such a manner that the operation of the motor from a power-supply of the `proper frequency will produce other beats in the receiver .which are of the correct frequency for those of the watch or clock under test. By listening to the two kinds of beats and with 'the aid of the adjustable contact assembly, the graduated dial, a calibration table and another time-keeping device, both the ,direction and the amount of the 40 error can be quickly and accurately determined.

The synchronous motor may, however, be replaced by some other mechanical device whose rate oi motion is regulated to the proper precision and is capable of making electrical contacts or causing electrical impulses which are of the proper frequency and which can be shifted in or out of phase with those of the apparatus under test. When used as a device for making the tests on the frequency of alternating current systems, or 'on rotary machines and the like, it also consists of two parts whose functions are similar to those just described; however, the apparatus required and often the circuit arrangements necessary are somewhat different as wlll be noted from the descriptions contained herein.

(c1. isi-f0.5)

With the above and other objects in view, which will become apparent as the description proceeds,

the invention resides in the construction, combination an'd arrangement of parts, hereinafter more fully described and claimed, and illustrated in the accompanying drawing,' in which like characters of reference indicate like parts throughout the several gures, of which.:

Fig. 1 is a front elevation showing the dial, the` indicator hand, the rotary switch and certain parts of the adjustable contact assembly.

Fig. 2 is a top plan view illustrating the assembly of the dial, the adjustable contact, the rotary switch and the synchronous motor.

Fig. 3 is an end viewof Fi`g.l2.

Fig. 4 is a diagram of the microphone-receiver Acircuit employed in connection with the testing of watches and clocks, and the frequencyofalternating current systems.

Fig. 5 is a diagram of the circuit for the testing of rotary machines.

The devices of vthis general character with which Iam familiar have proven decient in arrangement many respects, one of the principal defects being cal parts in order to de termine the direction of the error; another principal defectbeing that a single master device could be used for only one beat-frequency, rendering it necessary `to provide a separate master whenever apparatus designed to produce a different number of beats per second was to be tested. Therefore it was to provide accurate and efcient methods for making` the tests described herein,l without such deficiencies that I designed the devicev forming the subject matter of this invention. n

In the illustrated embodiment characterizing ythis invention there is shown an electrical synchronous motor A, a rotary switch mechanism B connected therewith, a graduatedmetallic dial` member C and an adjustable contact mechanism D carried by the dial member.

The small synchronous motor A,'which is of conventional construction and which may be similar to the motor used in a synchronous electric clock,is housed in a suitable casing I, in the present instance, rectangular in configuration and formed at each end Withlateral anges 2 adapted to be suitably bolted or otherwise Secured to a base plate 3 formed either of insulating or conducting material, though in the latter case the lao motor and also the dial plate C referred to below should be insulated from the base. Projecting from said casing i's motor shaft 4,`and mounted on its free end, keyed or otherwise suitably secured thereto, is the rotary switch mechanism B comprising wheel or disk member 5 formed with a series of equi-spaced radially extending contact arms, a, b, c, d, and e. The shaft 4 with switch mechanism B is adapted to have the proper speed of revolution for the device being tested. In practicing my invention I may e1ect to have the shaft 4 driven by the motor A through suitable adjustable speed change gearing, said gearing is not shown since the use of such gearing for the increase or decrease in speed of rotation of shafts is so generally understood and so widely used.

Secured to one end of base plate 3 by screws 6 is the dial plate C, in spaced relation with respect to motor A, formed on its face with a dial E, which is divided into five major divisions, each division being sub-divided into 100 parts and every tenth part numbered. It will be noted that the switch B has five contact points a, b, c, d, and e, which correspond with the flve major divisions F on the dial E, and while this number has been chosen for operating reasons it is to be understood that the number can be varied according to the particular operating requirements without departing from the spirit of the invention.

The adjustable contact mechanism D carried by the dial plate C comprises shaft 1 which is suitably journalled in said dial plate C in exact longitudinal alignment with shaft 4, and is formed with a iiange 8 on one side of said dial plate and has spring washer 9 mounted thereon and adapted to contact the opposite side of dial plate C against which said washer is securely maintained by lock nuts Ill threadedly mounted on shaft 1 and by which means said shaft is held in place. Keyed or otherwise securely fastened to the opposite or inner end of shaft 1 is an arm Vformed at its free end with a right angle .extension 4to which is suitably secured an outwardly and upwardly extending contact spring I2 the free end of which isA adapted to be engaged by the respective contacts a, b, c, d, and e during each revolution of switch B, as and for a purpose hereinafter more fully appearing.

Closely fitted on the shaft 1 adjacent to the flange 8 is a hand I3 whose resistance with the shaft is such that normally it will turn with the knob I4 which is secured to the free end of said shaft by set screw I5, yet sufficiently loose to permit being slipped manually in either direction. The mechanism D can be turned manually in either direction by knob I4. The lock nuts I0 are adapted to be so adjusted that the knob I4 can be readily turned though offering sufiicient resistance that mechanism D will remain set in position when the turning is discontinued and also affording sufficient pressure of flange 8 against dial plate C to insure a good electrical connection. Adjustment of contact spring I2 should be such that there will be just suflicient pressure of this spring against the switch points a, b, c, d, and e when the switch mechanism is rotating for good electrical contacts. The microphone-receiver circuit diagram illustrated in Fig. 4 and in which is mounted the motor and rotary switch assembly A-B and the dial plate and adjustable contact mechanism C-D will now be traced.

In the circuit diagram illustrated in Fig. .4 there is shown a primary circuit wherein the current flows from battery G or other source of power through Aconductor I6, microphone I1, conductor lar variation in the flow of current from the output of this amplifier, through conductor 22, volume control 23, conductor 24, receiver 25, conductor 26, and back to the amplifier. Since the audible beats or impulses of a watch, clock or other device to be tested when placed near the microphone will cause such variations in the flow of current in the primary circuit by effecting slight changes in the resistance of the microphone, which will in turn, as referred to above. cause similar variations in the fiow of current in receiver 25, the beats or impulses of a device H so placed will be heard in the receiver 25. It will be noted from the above that definite directions in the flow of currents through the secondary circuit, which includes coil S, etc., and also from the output of the amplifier 2| have been assumed. This has been done, however, merely to trace the circuits; the actual directions of iiow depend upon the conditions prevailinglor the ccnstruction of the apparatus or both.

To the section of circuit just described between amplifier 2| and receiver 25 there is connected through leads 29 and 30 another circuit in bridged or parallel relation, the object of the latter circuit being to transmit to the receiver for synchronization with the beats or impulses of the apparatus H under test, the beats or impulses caused by the making of contacts by the points a, b, c, d, and e on the rotary switch B with the spring I2 causing the receiver 25 and amplifier 2| to be momentarily shunted byv resistance 50 when the motor A is running. This circuit will now be described.

When such a contact is made direct current will flow from the output of amplifier 2| through one of its two conductors, suppose it be number 22, to point 28, through 'conductor 29 to the motor A, to the rotary switch B, which is grounded to the motor, through a contact point, a, b, c, d, or e', to the adjustable contact assembly D via the spring I2, of which it is a part, to the dial plate C against which Dis firmly pressed, through conductor 30, resistance 50, volume control 3| and conductor 26 back to the other side of the output of .amplifier 2|. This flow of current will result in changing the amount of current flowing through the receiver 25 and will thus result in producing a beat in the receiver. These beats will of course be produced as often as suoli contacts are made, since the making of contact between the spring I2 and contacts a, b, c, d and e will cause the receiver 25 and the amplifier 2| to be momentarily shunted by resistance 5D. It

is of course necessary for this operation that the output of the amplifier to have a direct current component such as would ordinarily result from the output or plate circuit of a thermionic tube amplifier. If I elect to equip amplifier 2|, with 'an output transformer as is well known to the art or arrange it otherwise to prevent the fiow of direct current in the output circuit 22, or if an amplifier is not used at all as referred to later,

I would insert a battery'or other low voltage lsource of electricity in series with the circuit of which conductor 30 forms a part in order toproduce the beats in receiver when the contacts of B and D are made. Fig. 5, which shows another application of my invention to be described below, shows such-a battery connected in conductor e 30.

Method of operation .-1When use d as a device for testing watches or clocks volume control 23 to adjust this sound in the however, is usually not required for clocks or the larger watches.-

When the motor A is running the rotary switch B is rotating and the points a, b, etc., are making contacts with the contact spring I2. As shown here a total of iive contacts are made between the spring and the points for each revolution of B. As the motor and the plate C are normally insulated from each other the making of these contacts results in momentarily connecting these parts electrically, and as they are bridged through resistance 50 across the microphone-receiver circuit described above a sound or click will be heard in the receiver whenever a contact is made.

Let it be assumed that a watch designed to have 300 beats or ticks per minute is to be tested.

(This is now the standard for most high grade watches the world over.) In this case the switch ,B would be geared by gearing not shown `but mentioned above to the motor to turn one revolue tion'per second or 60 per minute and would thus produce 5x60 or 300 clicks 'in the receiver per minute.

In preparing to determine the error the Watch to be tested shouldbe placed near the microphone and the volume control 23 adjusted until the beats of the desired volume are heard in the receiver. The motor should then be started and the volume control.3| adjustedI until the clicks or beats produced in the receiver by the making of the contacts referred to above, caused by the receiver 25 and amplifier 2| beingmomentarily shunted by resistance 5D, are approximately the same loudness as4 the beats of the watch.

'I'hus two sets of beats will be produced in the receiver. If at the same instant, this condition being referred to hereafter as synchronism or synchronization, they will be heard at the rate of 300 per minute, and will be a combination of the two types. If produced at different instants both 1440 (No. minutes per day) 300 (No. ticks per xriinutc)}=4`8 mmutes In like manner if it occurs once every fifteen seconds the error would be 19.2 minutes, if in thirty seconds 9.6 minutes, if in two minutes 2.4 minutes, and if in five minutes .96 minute, etc.

By turning theadjustable contact D by means.

of the knob Il synchronism or non-synchronism can be 'produced at will, this being the result of changing the instants at which the contacts ar made by the rotary switch B.

Suppose the beats of the Watch under test do not normally synchronize with the beats produced by the rotary switch B more than oncevin approximately 15 seconds and that the knob I4 istu'rned until synchronization is obtained; and suppose also that after a short time the beats are `slightly apart. By turning the knob in one direction the beats will become further apart but rection they will again ,be synchronized. If this synchronization is obtained by turning the knob in a clockwise direction fwherl using the arrangement shown in Fig. 1 the watch H under test would be running fast, but if in a counter-clockreceiver to the proper intensity. 'Ihis amplifier,

now be determined in accordance with the instructions given in the foregoing or in the succeeding paragraph as follows:

If the synchronization requires more than one minute, it will usually be desirable in order to save time to first synchronize the beats as before, and then slip the hand I3 to one of the zeros. After the beats become slightly apart the knob I4 should be turned until synchroniza tionis again obtained. As,` the turning of the knob also turns the hand, its reading in one hundredth part divisions from this zero will indicate the percent of synchronization and the error can be obtained from the table in the same manner as before.

The calibration table or chart referred to, which would be used in connection with this device, would indicate the amount of error in the running of the watch or clock under test during a xed time, ordinarily 24 hours, from the data obtained in the operation of the device.

Method of operation- When used as a. device for testing the frequency of alternating current systems When making .these tests the circuit arrange.

ment shown in Fig. 4 should be used and the verror is determined in the same manner as above de' scribed for watches or clocks with the following exceptions:

S (a) A standard watch or clock instead of one to be tested is placed near the microphone. (b) 'I'he indication of the direction of error is opposite to that in the other case. (c) A different calibration table 'is required.

For example, suppose synchronism occurred every three minutes when using a standard timepiece having 300 beats per minute. In this case the frequency of the system would be or 1,600 part ofi. For a 60 cycle system this would correspond to an error of or .0667 cycle per second.

TESTING or Ro'rAnY MACHINES Description of special arrangements required When it is desired to test the R. P. M. of rotary machines designed for constant speed operation such as a generator, a phonograph motor and the like, the mechanism under test must be adapted to produce the beats, and the circuit arrangement and hookup as illustrated in Fig. 5 may be employed. 'I'he rotary switch mechanism I is similar to switch B heretofore described and comprises disk 32 formed with radially extending contact arms f, g, h, and i, and with a hub or iiange portion 33 which is suitably connected to shaft 34 or other rotating part of the machine to be tested and the operation of said switch mechanism is similar to that of the rotary switch B heretofore described. 'Ihe brush J suitably mounted adjacent to said switch is adapted to bear securely against the flange 33 so as to make a good electrical connection therewith and the contact points of arms f, g, etc. make contacts in regular sequence with the contact spring K as the disk rotates, as will be well understood. Spring member K is also suitably mounted adjacent to said switch.` The current flows from battery L, through conductor 35, brush J, flange 33, disk 32, contact points f, g, h, and z' respectively, spring K, conductor 36, receiver 31, conductor 38, conductor 39, resistance 52, volume control 40, conductor 4I, back to battery L and through this circuit the beats from mechanism I in accordance with R. P. M. of shaft 34 may be heard in receiver 31. The circuit diagram in Fig. 5 from point X of conductor 29, through mechanism A-B and D-C, to point Y of conductor 30 is identical with the circuit described in Fig. 4. The current iiows from battery M through vresistance 5|, volume control 42, conductor 36, receiver 31, conductor 38, conductor 29, to X, through the mechanism A-B and C-D to point Y, through conductor 30, back to the other side of the battery, and through this circuit the beats or impulses from switch B of motor -A may be heard in receiver 31 for synchronization with the beats or impulses from switch I, which, as shown, is connected to the rotary machine being tested. It is the purpose of ref sistance 5l to prevent impulses from B completely masking those from J when the resistance of volume control 42 is reduced to zero, and likewise 52 prevents those from J masking those from B when the resistance of volume control 40 is reduced to zero.

Method of operation- When used as a device for testing rotary machines It Will thus be seen that the arms f, g, h, and i make contacts in regular sequence with the contact spring K as the disk 32 rotates. The making of these contacts momentarily connects together electrically the brush J and spring K and also the two leads to which these are attached,

-and on account of the battery L being in this circuit causes beats in the receiver. Likewise due to the battery M being inthe motor circuit contacts made by the turning of the rotary switch B will also cause beats inthe receiver in the same manner. By having the switch B operated by the motor at the proper speed, these beats will be of the correct frequency for those of the machine under test.

With both the machine shaft 34 and the synchronous motor A running and the'volume controls 40 and 42 adjusted until beats of the proper volume are heard in the receiverthe error in the running of the machine is determined in precisely the same manner as for a watch or clock; however, as in the testing of the latter,

the calibration table used must be designed so as to be applicable to the machine.

For example, suppose the disc 32 .is attached to a phonograph motor which is designed to turn '78 revolutions per minute. As it is shown equipped with four contact points the synchronous motor with associated gearing mentioned above would be operated to make rZ8 4 or 312 contacts per minute. Suppose also that synchronism occurred once every 10 seconds. In this case the phonograph motor would be running one revolution in error every 40 seconds (l0 sec.) 1/4 I it would be practical when testing rotary machines to have the adjustable contact mechanism'in the circuit with the latter switch and.

the iixed contact in the former, instead of the reverse arrangement as shown. The tests'would then be made in the same manner as those described though the indication of the direction of error would be opposite tothat in the other case.

From the above it will be apparent that I have designed a unique device for determining the error in the running of machines by the synchronization of sounds, `simple in construction, versatile in its adaptive use, manufacturable at a minimum cost, andeiicient for the .purposes intended. l*

Although in practice I have found that the form of my invention illustrated in the accompanying drawing and referred to in the above description as the preferred embodiment is the most emcient and practical, yet realizing that conditions concurrent with the adoption of` my invention will necessarily vary, I desire to emphasize that various minor changes in details of construction, proportion and arrangement of parts, may be resorted to in the scope of the appended claim without departing from or sacrificing any of the principles of this invention.

Having thus described my invention, what I' circuit to said amplifier input circuit, an ampliiier output circuit including a receiver and connected'with the amplier, said amplier output A I 2,126,140 -circuit being adapted to receive amplified signals at the frequency of the input signals, a master device circuit, and means in said master device circuit for producing signals at a predetermined frequency, said means including a rotary switch comprising a motordriven shaft, a disk keyed to the shaft, a series of circumferentially spaced arms radially projecting from the periphery of said disk and constituting a. plurality of rotary contacts, a normally stationary adjustable contact positioned in the path of and adapted to be engaged by said rotary contacts, means connecting said master circuit to the output circuit of said amplifier, said means includingl a variable resistance whereby signals at the frequencies of said master device circuit and said lmicrophone input circuit are simultaneously impressed upon said amplifier output circuit, and means in connection with said switch* for circumferentially adjusting said stationary contact with respect to said rotary contacts for the purpose of shifting the signal frequencies of the master device circuit into and out of phase with the 'signal frequency l0 of the ampliiler output circuit.

PRENTISS BOYD AGNEW. 

